GitHub - mikeakers/DuoDevOverlay: Debug overlay for iPhone Duo apps that draws safe-area insets, the fold and the camera regions live over your UI

A debug overlay for iPhone Duo apps. It draws the safe-area insets (blue) and the reserved regions — the fold (orange) and the cameras and status block (pink) — over your running app, with a draggable panel of the exact numbers. It updates live as the device folds and rotates.

Add it

In Xcode: File ▸ Add Package Dependencies…, enter https://github.com/mikeakers/DuoDevOverlay, and add the DuoDevOverlay library to your app target.

Turn it on

In your UIWindowSceneDelegate:

import DuoDevOverlay

func scene(_ scene: UIScene, willConnectTo session: UISceneSession,
           options connectionOptions: UIScene.ConnectionOptions) {
    guard let windowScene = scene as? UIWindowScene else { return }
    // … set up your window …
    #if DEBUG
    DuoDevOverlay.install(in: windowScene)
    #endif
}

DuoDevOverlay.uninstall(from:) removes it and isInstalled(in:) tells you whether it's there — handy for a debug-menu switch. The panel's Hide overlay button uninstalls it too. Drag the panel anywhere; double-tap it to send it back to its automatic corner.

To keep a switch in step, including when someone taps Hide overlay, observe DuoDevOverlay.didChangeNotification. It's posted on every install and uninstall, with the scene as its object:

NotificationCenter.default.addObserver(
    self, selector: #selector(overlayDidChange),
    name: DuoDevOverlay.didChangeNotification, object: windowScene)

@objc func overlayDidChange() {
    overlaySwitch.isOn = DuoDevOverlay.isInstalled(in: windowScene)
}

Callable from iOS 17; it does nothing below iOS 27.1, where the reserved-region APIs don't exist.

What it can and can't see

The overlay is its own window above your app's, so it stays on top of modals and every touch outside the panel reaches your app. A window of its own sees window-level geometry: the status bar, home indicator, fold and cameras. Insets that your own navigation bars and tab bars add live inside your view controllers, so they don't show here.

Demo apps

DuoDevOverlayDemo.xcodeproj has two:

• DuoDevOverlayDemo: SwiftUI, with switches for a toolbar, navigation title and tab bar, to see how each one changes the safe area.
• DuoDevOverlayUIKitDemo: a plain UIKit app with the overlay installed the way your app would install it.

License

MIT — see LICENSE.